Deburring chambers are used for thermal deburring. Under the influence of heat and pressure, a chemical process starts in which burrs, flashings, and other imperfections are burned off, and thus removed upon subjecting the workpiece to a temperature and pressure shock. The required temperature shock is generated by combusting the mixture of combustion gas and oxygen. It is necessary to compress the gas mixture before combustion in order to obtain the necessary energy. The deburring effect is increased if the energy, and hence the pressure is increased. Combustion temperatures which occur within the chamber during combustion are in the range of between about 2500.degree. to 3500.degree. C. With increase of pressure, the amount of heat per volume-unit liberated by the combustion is also increased. The pressures within the combustion chamber before combustion, that is, the pressure of the combustion gas-oxygen mixture is in the order of about 40 bar.
Known apparatus to treat workpieces in a combustion chamber, particularly for thermal deburring, utilize deburring chambers of various sizes. Deburring chambers having diameters of about 17 cm, 20 cm, 25 cm with a height of about 15 cm are used. Such chambers are introduced into frame structures which generally have a C-frame, that is, one upright member secured to a base and a top laterally projecting element. It is also known to utilize deburring apparatus which are constructed in "portal" form, that is, two upright members with a cross piece on top secured to a base, that is, generally in the shape of an inverted U. When using chambers in this "portal" construction, diameters of up to about 32 cm, with a height of 30 cm can be used.
The size of the deburring chamber to be employed depends on the workpiece to be treated, or the quantity of small workpieces. The required energy also depends on the size of the chamber. It is desirable to have the dead space within the chamber, that is, that volume which is not taken up by the workpiece as small as possible to utilize the combustion gases and oxygen most efficiently.
In accordance with structures which are presently available, the size of the machine frame is matched to the size of the deburring chamber. Thus, a deburring system with a small deburring chamber has lower vertical columns than one with an axially larger chamber. Consequently, various machine frames are needed for the various deburring chambers. The flexibility of use of such apparatus, thus, is low. It is uneconomical to operate a deburring chamber of larger size than necessary for the workpiece if a smaller deburring chamber would be sufficient. The larger chamber has a higher energy consumption. It has been determined that it would be commercially and economically desirable to utilize different sizes of deburring chambers for different operations, that is, to carefully match the quantity and nature of workpieces to the size of the chamber being used.
The invention: It is an object of the present invention to provide a thermal and high-pressure article treatment system in which the overall energy consumption is only such as is absolutely necessary for treatment of the workpieces, and in which the size of combustion chambers can be adapted to the quantity, or size of the workpiece to be treated.
Briefly, the apparatus is constructed in form of the "U" configuration, that is, two vertical support columns with a cross member secured to a base. A worktable is moveable upwardly towards a chamber suspended from the cross element. In accordance with the invention, a set of essentially bell or inverted cup-shape chamber structures is provided, each structure fitting within the frame. A set of adapters is provided, which are located between the respective chamber of the set and the upper cross element of the frame to permit positioning the lower edge of the chamber structure at an approximately uniform height with respect to the worktable, regardless of the axial length of the specific chamber structure then being used.
By providing a set of chambers, and a set of adapters, which are mutually matched to each other and to the frame structure, the apparatus is substantially more versatile in use; the respective working chamber can be quickly installed and exchanged for another one if a different workpiece is to be treated. Optimum working conditions, and minimum operating costs will pertain. The utilization of fuel gas, and oxygen is minimized, and the liberated energy is efficiently used.
In accordance with the present invention, any size of workpiece, or combination of workpieces is matched to the optimum size of the chamber. Only a single machine frame is used, capable, however, of receiving the various chambers of the set. Differences in dimensions are then compensated for by the set of adapters. Consequently, the machine frame, designed for the largest one of the chambers to be utilized can be used for various other chambers, of smaller axial lengths, for example. For the largest chamber, no adapter need be used.
If a small working chamber is all that is needed, a suitably dimensioned and matched adapter is used, for example in the form of an intermediate adapter ring, in order to match the smaller combustion chamber to the machine frame. The length of the adapter is increased as the chamber decreases. Thus, each chamber has an appropriate associated adapter. It is, thus, possible to install a single treatment apparatus, and, nevertheless, handle small workpieces economically and efficiently.
The adapters preferably have suitably fitted connecting flanges and centering surfaces, so arranged and positioned that the overall system can readily be changed over for use of the most appropriate treatment chamber.
The system has the additional advantage that, in accordance with the preferred feature of the invention, it can readily be utilized with a well-known coding system. Since various working chambers of various diameters can be used, the filling quantity, and the filling pressure must be matched to the size of the working chamber. This, also, controls the explosion pressure. The effect of deburring is increased as the pressure in the working chamber increases. In accordance with a feature of the invention, a coding system is used which is secured to, or associated with the respective working chambers and is used as an information transfer system for the gas metering and gas pressuring pressurization device, so that the appropriate quantity of oxygen and combustion gas is supplied with the appropriate pressure for the particular combustion chamber then installed in the machine. Each one of the combustion chambers of the set thus is characterized by the particular code used, so that the treatment process can be matched to the particular chamber size then in use. Thus, every chamber will receive the appropriate quantity of combustion gas and oxygen, with the appropriate pressure, so that the mixture will have the appropriate concentration at the appropriate pressure. This is also of importance since the metering cylinders will supply only so much of the respective gas as is necessary to fill the chamber. This is a safety measure to prevent flash-back and explosions. Small volume combustion chambers, thus, are coded for a smaller metered supply, and smaller metering strokes of a gas supply valve than chambers of high volume. The coding, thus, can be utilized to provide a command filling pressure and a command filled gas volume for the metering system. The coding system, thus, has the advantage that the metering of the respective gases, introduced under substantial compression, is controlled directly by the particular chamber being used. The compression of the respective gas components is the same and, towards the end of the fill of the combustion chamber, will conform to the pressure within the chamber which is necessary for optimum operation of the combustion event. With increase of pressure, the heat liberated, per unit volume, increases. The quantity of gas to be filled by the metering and pressurization valves, for example reciprocating valves injecting a predetermined quantity of combustion gas and oxygen, respectively, thus can be controlled to provide the appropriate quantity in dependences on the particular chamber then in operation.
Suitable gases, to be mixed with oxygen, are natural gas, methane or hydrogen.
In accordance with a preferred feature of the invention, the coding system utilizes slideable coding bolts, and/or cam surfaces, located on the working chamber and providing output signals, for example by position, characterizing the respective data to be sensed, which then can be sensed by suitable pickups or sensors. This provides a simple arrangement in which the overall system can readily be associated with a coding system insuring safe and optimum operating procedures, although various sizes of work chambers can be used, having substantial differences between themselves.
Safety is further enhanced, in accordance with the preferred feature of the invention, by so arranging the chambers and the adapters that only associated adapters and chambers can be fitted together unambiguously so that, for example, an axially long adapter cannot be associated with an axially long combustion chamber.
The system is not restricted to thermal deburring apparatus; similar apparatus can be used for other purposes, for example for treating foamed articles, see for example German Pat. No. 1,504,096, or to remove connecting pores in porous structures, see for example German Pat. No. 2,322,760. The present invention, thus, is particularly directed to sets of chambers which permits treatment of the workpiece within the chamber by an explosive gaseous mixture.